Viscosity of Solids and its Physical Verification. 203 





Strain. 



Molecular stability. 



First twist... 

 Second twist. 

 Third twist, . 

 Fourth twist, 

 Fifth twist... 



— T 



+ T + AT 



-t+\t-A't 

 + r + A 2 r-A 1 'r+A"r 

 -r+A 3 r-A 2 V + A,"r-A'"r 

 etc. 



+n— An 



•{-n—A^i — A'n 



+w— A. 2 ii — A^n— A"n 



-\-n — A~ z n — A 2 'n— A/'w— A'"n 



The variation which A undergoes in passing from one twist 

 to the next is indicated by subscripts. Thus At, A : t, A 2 t, . . . 

 is probably a decreasing series; whereas An, A^, A 2 n, ... is 

 an increasing series, because reversal of the sign of the twist 

 must be supposed to reconstruct some of the configurations 

 broken up by the preceding twist. The first part of the scheme 

 indicates that the strain in the 2nd, 4th, 6th, .... twists is 

 necessarily greater than the strain in the immediately pre- 

 ceding 1st, 3rd, 5th .... twists respectively ; at least at the 

 outset of the experiments. Hence the observed oscillations. 

 Again, the number of unstable configurations must continually 

 decrease, according to the second half of the scheme. Hence 

 the mean line about which the observed viscous deformations 

 oscillate. Finally, experiment shows that the accelerating 

 effect of At on viscous deformation is greater than the retarding 

 effect of —An. After this, however, the accelerating effect of 

 A. 2 t— AjV + A"t and the succeeding T-quantities, is invariably 

 less than the retarding effect of — A 2 ?i — A/n — A n n and the 

 succeeding n-quantities respectively. For general purposes 

 the scheme may be simplified. The fact that this phenomenon 

 is reached by Boltzman's mathematical theory is one of its 

 strong features. Of course the period of oscillation is arbi- 

 trary. 



86. The second part of Table IV. shows that the viscosity 

 gained in virtue of consecutive alternate twisting of glass-hard 

 steel is permanently gained. Left to itself, the rod does not 

 recuperate, inasmuch as the amount of viscous deformation 

 observed after several days has only increased insignificantly. 

 Mere molecular motion has therefore permanently broken the 

 more unstable carbon configurations. I must waive this sin- 

 gular result here, since it cannot be fully interpreted without 

 electrical research. I will only note, therefore, that the viscous 

 effect of prolonged twisting to and fro in case of glass-hard 

 steel is of the same order of magnitude as the effect of pro- 

 longed annealing at 100°. This indicates the importance of 

 the motional effect, 



